1. Field of the Invention
The present invention relates to an automatic accompaniment apparatus, and more particularly to an automatic accompaniment apparatus capable of performing an automatic accompaniment having much variety with less storing amount of information.
2. Prior Art
An automatic accompaniment apparatus has been developed which detects a root tone and a chord from key depression data of an accompaniment keyboard and performs an automatic accompaniment based on the detected result and selected rhythm pattern.
The conventional automatic accompaniment apparatus includes an apparatus which only generates rhythms at the same tone pitch in correspondence to a rhythm pattern; an apparatus which plays a variety of bass tones based on tone pitch data stored in advance together with the performance of chords (Japanese Patent Laid Open Publication No. 59-140495); an apparatus which effects an automatic accompaniment of chords corresponding to key depression data of a keyboard (Japanese Patent Publication No. 60-23355 etc.); and an apparatus capable of resulting in a special effect of a performance (background performance effect) by generating musical tones of an accompanying chord successively by the predetermined timing in a shifting manner (Japanese Utility Model Publication No. 57-93995 and the like).
However, the above conventional apparatus has the following drawbacks. The apparatus which generates only rhythms at the same tone pitch lacks musical variety, and the apparatus storing tone pitch data must store large amount of patterns. In particular, the latter preferably changes not only bass tones but respective tones composing a chord to effect an automatic performance full of musical variety, which, however, given rise to the problem that an amount of tone pitch data which must be stored is increased.
Incidentally, when chords are actually played by a human player, a change in a part of tones composing a chord is effected in such a manner that only a finger corresponding to a tone to be changed is moved and keys for common tones remain depressed in many cases. More specifically, the common tones composing the chord are often played by a tie expression.
However, in the conventional automatic accompaniment apparatus, all the tones are repeatedly generated, and then the more natural effect of a performance is difficult to achieve.
In addition, since the conventional automatic accompaniment apparatus for generating tones composing a chord in the shifting manner cannot control a shift interval, it lacks variety of performance effect.
The conventional automatic accompaniment apparatus has also a drawback that delayed tones composing a chord are generated after a chord at the next timing and the performance becomes musically unnatural.